Biphenyl Columns Provide Good Separation of the Glucosides of DIMBOA and DIM 2 BOA

Abstract

Hydroxamic acids are important defense compounds in cereals and have been subject to extensive research. Two important hydroxamic acids in maize are 2-β-D-glucopyranosyloxy-4-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA-glc) and its 8-methoxylated derivative (DIM₂BOA-glc). The compounds are typically reported as resolved by mass spectrometry rather than chromatography, with DIM₂BOA-glc quantified relative to DIMBOA-glc. Biphenyl HPLC columns, however, allow good separation of the two compounds at both the analytical and semi-preparative scale, enabling both isolation and absolute quantitation of both compounds. In combination with established sample treatment and chromatographic methods, biphenyl chromatography thus promises new possibilities for resolving benzoxazinoid glucosides.